Real-world Effectiveness of the SARS-CoV-2 mRNA Vaccines in Preventing Confirmed Infection in Patients on Chronic Hemodialysis

Abstract

Background

Persons on chronic hemodialysis have a significantly diminished humoral immune response to SARS-CoV-2 vaccines. Whether this translates to reduced vaccine effectiveness (VE) is unknown.

Methods

We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify all Veterans who were tested for SARS-CoV-2 between January 26, 2021 and August 31, 2021. Using International Classification of Diseases, 10 th edition codes and attendance at a dialysis clinic or center, we identified those who were on chronic hemodialysis. We used a test-negative, case-control design using a doubly-robust logistic regression model to determine the VE of the BNT-162b2 (Pfizer) or mRNA-1273 (Moderna) vaccines in preventing confirmed SARS-CoV-2 infection.

Results

Among 847,199 Veterans tested for SARS-CoV-2 between January 26, 2021 and August 31, 2021, there were 6,076 Veterans on chronic hemodialysis. Among those, we identified 1,270 cases (580 fully vaccinated) and 2,959 controls (2,120 fully vaccinated). The overall VE >14 days after the second dose in preventing documented infection was 68.2% (95% CI:62.6,72.9). VE was 68.9% (95% CI:61.9,74.7) for Pfizer-BNT-162b2 and 66.7% (95% CI:58.9,73.0) for Moderna-mRNA-1273 vaccine. There was no difference in VE by age (<70 vs. >70 years), race or sex. There were no events recorded in persons with a Charlson’s comorbidity index score of <2.

Conclusion

VE of two doses of current mRNA vaccines in preventing SARS-CoV-2 infection in persons on chronic hemodialysis is lower than historic VE rates in the general population. Effect of additional doses in improving VE in this special population needs further study.